Engine starter coupling mechanism



'Sept. 11, 1956 H. HOEFENER EI'AL 2,762,224

ENGINE STARTER COUPLING MECHANISM Filed May 23, 1955 FIG. 1

INVENTORS HE NR) TROEGE/P HOWARD HOEF 5 NE A AITOR/VE) United ratestuatent Q ENGINE STARTER COUPLING MECHANISM Howard Hoefener, Teaneclr,and Henry Troeger, Ramsey,

N. 1., assignors to Bendix Aviation Corporation, Teterboro, N. J., acorporation of Delaware Application May 23, 1955, Serial No. 510,446

7 Claims. (Cl. 74-7) This invention concerns new and useful improvementsin engine starters. It is more particularly concerned with enginestarter mechanism for coupling the starter to the engine and forautomatically uncoupling the same.

The mechanism of the present invention finds particular use inassociation with high speed engines, such as might run at a speed of18,000 R. P. M. At this high speed conventionally used restoring springsare apt to bind, and are ineffective to restore the starter jawmechanism after the engine has started.

A general object of the invention is to provide starter mechanismsuitable for association with such high speed engines.

A further object of this invention is to provide novel and improvedmeans for restoring the starter jaw of starter mechanism associated withhigh speed operating engines.

A still further object of the invention is to provide an inertiafiyweight type mechanism for efiecting engagement of a starter jaw withan associated engine and for effecting subsequent restoration of thestarter jaw.

The invention further lies in its particular construction,

in the arrangement of its elements, and in their particular combinationsand cooperative association with one another to effect the purposesintended. The foregoing and other objects and advantages of thisinvention will appear more fully hereinafter from a consideration of thedetailed description which follows, taken together with the accompanyingdrawings, wherein an embodiment of the invention is illustrated. It isto be expressly understood, however, that the drawings are for purposesof illustration and description and are not to be construed as definingthe limits of the invention.

In the drawings:

Fig. l is a longitudinal section through engine starter mechanismembodying the invention; and

Fig. 2 is a fragmentary left end view of Fig. 1.

In describing the invention in further detail, reference is directed tothe drawings, wherein there is disclosed a starter main drive shaft 1supported for rotation in proper bearings 2 and adapted to be driven bysuitable motor means, not shown. An elongated barrel member 3 surroundsthe drive shaft, and is engaged for rotation with the latter by asuitable slip clutch 4, here of the discpack type. A member 5 fixed uponthe drive shaft and forming part of the slip clutch provides a radialflange 6 that serves as a backing plate for the clutch pack. Surroundingthe left end of the drive shaft is an elongated cylindrical axialextension 7 of member 5. Sleeving extension 5 and axially slidablethereon is the shaft end 8 of a starter coupling member 9. The jaw head10 of the latter is engageable with an opposed complementary jaw head 11of an associated high speed type engine drive shaft. The starter jawshaft 8 is slidably engaged at the left end thereof by straight splinesat 12 with complementary splines of a surrounding screw member 14. Thescrew member is in turn engaged, as at 15, by external helical threadswith complementary threads in- 2,762,224 Patented Sept. 11, 1956ternally of a surrounding extension 16 of the barrel member. By thisstructure, it is clear that rotation of the barrel member will carry thescrew member 14 and the starter member 9 about with it.

Novel means generally indicated at 18 is operable to exert a draggingaction upon the sore" member 14 as the barrel member rotates. Thiseffects axial advancemen of the screw member to the left.

This movement of the screw member operates to advance the starter jawhead into engagement with the associated engine jaw. To effect this, theright end of the starter shaft carries a heavy ring 19 which limitsagainst a snap ring 21 fitted in the interior wall of the screw member.A coil spring 22 about the starter shaft, limited at one end by thesplines 12 of the screw and starter shaft and limited at the other endby the heavy ring 19, holds the starter jaw in its normal position. Inthis position the ring 19 is limited against the snap ring 21 of thescrew member. By this structure it is plain, that leftward advancementof the screw member will slide the starter jaw member along with it.

The novel means indicated at 18 for effecting axial advancement of thescrew member and of the associated starter, also serves to effect returnof these members. This screw advancement and return means comprises aplurality of heavy lugs 23 pivotedly mounted in radial slots 24 formedin a thickened rib 25 projecting from the marginal end of the left faceof a radial end flange 26 of the barrel member. The lugs 23 are four innumber, spaced equally apart, though only two are shown in Fig. 1. Thesecooperate with the screw member to cause the latter to be advanced forengine starting operations and to be returned during starterdisengagement operations.

A lug 23 comprises a pair of unitary broad faced stub arms 27, 28substantially at right angles to one another. The lug pivots at its apexcorner on a pin 29. Lug arm 28 has formed in its free end a segment ofteeth 31 which are normally engaged with relatively broader straightsplines or teeth 32 formed about the left end portion of the screwmember. As shown in Fig. 2, the center of gravity CG of the lug islocated in the body portion thereof at a point removed from the pivotpoint. The force of gravity acting on the lug weight tends to rotate itclockwise about its pivot (Fig. 2), thereby exerting a pressure tryingto turn the screw member engaged therewith in the opposite direction. 1

In the operation of the device, upon rotation of the main shaft 1, thebarrel and screw members are carried around with it, herecounter-clockwise (arrow Fig. l). The heavy lugs 23, because of theirinertia, do not accelerate as rapidly as the barrel member and, as aresult, the lugs turn on their pivots in the direction of the arrow(Fig. 2). This eifects a dragging action upon the screw member,whereupon the latter is caused to travel axially outward. As the screwmember so moves, the starter jaw is advanced by it into engagement withthe opposed engine jaw. Whereupon, continued acceleration of the maindrive shaft cranks the engine.

Now, as the associated engine starts, it soon attains a high rate ofspeed, sufficient to carry on without the aid of the starter mechanism,whereupon the motive power to the main drive shaft 1 of the starter iscaused to be cut off in suitable manner. As the associated engine isadvanced to this high rate of speed, which may be 18,000 R. P. M., thelugs 23 tend to swing centrifugally in a counter-clockwise direction(Fig. 2). As the faster rotating engine jaw releases itself from thestarter jaw, the reaction efiected on the screw member by thecentrifugally acting lugs causes the screw member to be returned todisengaged position in the barrel member.

It is to be noted that projecting from the inner face (Fig. 1) of eachlug is a pin 33. The periphery of a ring spring 34 limits against theunderside of each pin. This serves to effect a slight radially directedtension through the pins upon the lugs, whereby chattering of the lugs,which might otherwise occur in engine startingoperations, is avoided'While an embodiment of the invention has been illustrated and describedin detail, it is to be expressly understood that the invention is notlimited thereto. Various changes can be made in the design andarrangement of the parts without departing from the spirit and scope ofthe invention, as the same will now be understood by those skilled inthe art; and it is our intent therefore to claim the invention not onlyas shown and described, but also in all such forms and modificationsthereof as may be reasonably construed to be within the spirit of theinvention and the scope of the appended claims.

What is claimed is:

1. In a high speed engine starter mechanism including a main driveshaft, a barrel surrounding the shaft, and slip clutch means engagingthe barrel with the main drive shaft for rotation with the latter, anaxially slidable starter jaw member, screw means helically engaged in anend of the barrel and arranged to advance axially out of the latter toslide the jaw member upon a drag being placed upon the screw means asthe barrel member rotates, and weighted toothed means pivoted to thebarrel member and cooperable with complementary toothed means about thescrew to exert a drag upon the latter so as to advance the screw memberaxially upon rotation of the barrel member.

2. In a high speed engine starter mechanism includ ing a main driveshaft, a barrel member surrounding the shaft, slip clutch means engagingthe barrel for rotation with the shaft, starter advancing screw meanshelically engaged to the barrel member and adapted to advance out of thelatter upon a drag being exerted on the screw as the barrel memberrotates, means for exerting such drag comprising a toothed lug memberpivoted to the barrel member and engaged with complementary teeth aboutthe screw member, the toothed lug having a center of gravity continuallyexerting while at rest a force upon the screw member in a directionopposed to the directional rotation of the barrel member.

3. In starter mechanism including a drive clutch barrel member, a screwmember helically engaged in the latter, and means for advancing thescrew out of the barrel member, said latter means comprising a pluralityof equally spaced toothed segments pivoted about the barrel member andengaging complementary teeth about the screw member, and a weighted armunitary with the body portion of each toothed segment normally tendingto pivot the toothed segment in a direction opposed to the directionalrotation of the barrel member.

4. In the combination of a driven barrel member, a

screw member helically engaged integral to the barrel member, and aflange formed'about an end of the barrel member, a plurality of lugsspaced equally from one another about the end face of the flange andpivoted to the latter, each lug comprising a pivot apex corner, atoothed segment arm and an arm at right angles to the latter, the centerof gravity of the lug being in the body of the lug removed from thepivot point, and the toothed portion of the segment arm being engagedwith a complementary toothed surface of the screw member, the force ofgravity acting on the lug tending to urge the screw member in aparticular angular direction relative to the barrel mem-.

her.

5. In engine starter mechanism of the character described including adriven barrel member having an end flange and a starter advancing screwhelically engaged internally to the barrel member, heavy toothed lugmeans pivoted about the face of the end flange and engaged with pinionteeth about an end of the screw member,

the toothed lug means having a center of gravity 01f vertical positionrelative to the pivot point of the lug means when the toothed lug meansand pinion teeth are engaged.

6. For use in association with a barrel member of the characterdescribed and for engagement with the pinion teeth of a starteradvancing screw of the character described helically engaged in thebarrel member; a heavy lug, having an apex pivot pin corner and a pairof stub arms at right angles to one another, one of the arms having atoothed segmentengageable with the pinion teeth of the starter advancingscrew, and the center of gravity of the lug being in a web portion ofthe lug between the arms and removed from the pivot pin corner.

7. In the barrel member of a clutch pack of the character describedincluding a screw member helically engaged at one end in an end of thebarrel member and having pinion teeth in the, peripheral surface of itsopposite end, an annular thickened. rib marginally about the end face ofa flange of. the barrel member, a plurality of slots radially throughthe rib member, and a heavy lug member in each .slot pivoted on a pincrosswise of each slot, the lugmember having a pivot point eccentric tothe axis of the lug and having atoothed segment in an end thereofengageable with the pinion teeth, the weight of the lug tending to urgethe toothed segment angularly in a particular direction and thereby to,urge the screw member angularly in the opposite direction.

No references cited.

